Managing slope risk for a large highway network

New South Wales (NSW) occupies the SE of Australia and extends over an area roughly 1200 1000 km (Fig. 1). Slope risk is concentrated in the area within about 300 km of the east coast, which is dominated by the Great Dividing Range. The range runs parallel to the coast, generally rising to between 1000 and 1300 m above sea level and locally to over 2000 m. The eastern escarpment of the range is steep and deeply dissected by short rivers. The western side falls more gently and grades into a gently sloping, predominantly alluvial plain which extends to the western border.